Microwave method - Add the white chocolate, cream, butter and glucose syrup (corn syrup) into a large microwave safe bowl. Microwave for 20 seconds at a time, mixing each time until completely melted and smooth.

Double boiler method - Fill a medium sized pot ⅓ of the way with water. Bring to a boil. Place a heat-proof bowl on top and turn the heat to low. Add all the ingredients into the bowl. Gently mix until mixture is completely melted and smooth.

To set - Directly cover the ganache with plastic wrap so that it doesn’t form a skin and set aside to set at room temperature. It will be firm to touch but slightly soft when fully set.

Softening the ganache (to do right before frosting) - Once the ganache has set, soften it by placing back in the microwave for 10 seconds, and mix with a spatula until it reaches a soft, spreading consistency. You can also do this by placing it on a double boiler and warming very slightly until you reach a spreadable consistency.

Finish buttercream - Add the softened butter to the bowl with softened ganache and use a handheld electric beater or stand mixer with a paddle attachment to whip together on medium high speed for 5 minutes. Stop the mixer and scrape down the bowl using a spatula. Beat again on medium high speed for a couple more minutes until evenly mixed. Then turn the mixer down to medium low speed and beat for 5 minutes. This low speed will give you ultra soft frosting.

Preheat a fan-forced oven to 150C / 300F (170C / 340F for no fan). Spray two 20cm / 8-inch cake tins with oil or brush with melted butter and line the bottoms with baking paper.

Heat the chocolate, milk and butter - Add the milk, white chocolate and butter to a heat proof jug and microwave for 2 minutes. Use a whisk or spoon to mix until chocolate and butter are fully melted. You can also do this in a heat proof bowl over a double boiler.

Add remaining wet ingredients - add the sour cream, vegetable oil and vanilla extract and whisk to combine. Set aside.

Combine dry ingredients - Add the flour, baking powder and salt to a small mixing bowl and use a whisk to combine.

Beat the eggs - Add the eggs to a large mixing bowl and use an electric mixer to beat until frothy. This can also be done in a stand mixer with a whisk attachment. While the mixer is on high speed begin slowly adding the sugar. This should take about a minute. Once it’s all in there, continue beating on high speed for about 6 minutes until it’s pale and thick and tripled in size.

Add dry ingredients to egg mixture - Add the dry ingredients to the eggs and use a spatula to fold through until no dry ingredients are showing taking care to scrape from the bottom where the dry ingredients like to hide.

Add chocolate mixture - Add ½ of the chocolate mixture. Use the spatula or whisk to gently fold through. Add the remaining chocolate mixture and fold through until the mixture is well combined and even in texture. It will be thin, with a little volume and fall out of the bowl into the cake pans in a thin ribbon.

To finish the batter - Add ½ of the white chocolate mixture and all of the oil and vanilla extract. Use the spatula or whisk to gently fold through. Add the remaining white chocolate mixture and fold through until the mixture is well combined and even in texture. This batter is very thin but still has a little volume and will fall out of the bowl into the cake pans in a thin ribbon.

Bake - Split the batter between the two baking tins and bake both cakes in the middle rack for 40 minutes. Once baked, allow to cool in the cake tin until warm, then gently run a knife around the inside edge of the cake to loosen. Allow to cool completely on a cooling rack.

Soften the chocolate - place the chocolate bar on a heatproof plate and microwave for 10 seconds. You don’t want to melt the chocolate; you just want to slightly soften it.

Shave - use a vegetable peeler to peel away curls of white chocolate over a baking tray. Pop them in the fridge to chill them for about 20 minutes. This will make them easier to handle when putting them on the sides of the frosted cake.

Trim the cakes - Use a large, serrated knife or cake leveler to trim each cake in half, giving you 4 cake layers. If the top of your cake baked in a dome shape, trim some of it away to level it so it’s flat before trimming the cake in half.

To layer the cake - Add some frosting to your serving plate and use an offset spatula to spread around. Add your first layer of cake and then add about ½ cup of frosting. Spread the frosting around evenly before adding the next layer of cake until all layers are on.

To cover the cake - Frost the outside of your cake using the rest of the frosting. No need for it to look perfect. We want luscious waves of frosting. Finish by adding the chocolate curls on the sides. This is a messy process so having a baking tray underneath the cake to catch the chocolate curls can make things easier.